Temperature control for hydraulic cushions



April 5, 1938.

F. J. RODE TEMPERATURE CONTROL FOR HYDRAULIC CUSHIONS Filed March 12, 1935 Patented Apr. 5, 1938 UNITED STATES PATENT OFFICE TEMPERATURE CONTROL FOR HYDRAULIC CUSHIONS This invention relates to power presses and is more particularly directed to a press having a hydraulically cushioned pressure pad.

The primary object of the invention is the provision of means to increase the operating capacity of the press by controlling the working temperature of the liquid used to cushion the pressure pad, so as to increase the possible length of stroke of a press operating ata given speed, or to increase the number of strokes per minute which can be attained by a press having a given slide travel.

Other objects and advantages of the invention will become apparent as the description proceeds, reference being had to the accompanying drawing which illustrates one embodiment of the invention and in which Figure l is a diagrammatic side view of a press with the pad and cushion parts in section; Fig. 2

is a detail elevation of one of the temperature control coils; Fig. 3 is an end view of the coil taken on line 3-3 of Fig. 2; and Fig. 4 is a schematic arrangement of the circulating system for the temperature control medium.

Referring to the drawing, my invention is shown in connection with a press l'having a stationary bed 3. A centrally disposed pressure pad 5 is provided in the path of travel of the main slide of the press in a manner well known in the art. The pressure pad is carried at the upper end of a stem 1 which carries a piston 9 at its lower end for controlled reciprocation in a cushion cylinder II. The cushion cylinder is adapted to be filled with oil or other suitable liquid from a surrounding reservoir I3 through a centrally disposed passage l5 leading from the reservoir. A suitable valve I1 is disposed in the passage ii to control the flow of liquid therethrough. The valve may be operated in any suitable manner, and in the form disclosed is actuated by a piston 2| working in a cylinder [9. The piston I9 is movable in either direction by air pressure either on its upper or lower side depending on whether it is desired to open or close the valve i1. 0bviously any other valve controlling device may be used as it is well known in the art to substitute a liquid controlling means for the pneumatic means disclosed.

It has been found in practice that as the pressure pad 5 descends and the piston 9 forces oil out of the cylinder ll the oil shows a marked rise in temperature due to the friction which it encounters in passing restricted parts of the passage around the valve II. In use, it is desirable to lock the pressure pad in its lowered position by closing the valve -n and holding the parts until the main forming die (not shown) has completed substantially a half of its up-stroke, thereby preventing deformation of the formed metal by reason of a premature raising of the pressure pad. 5

The valve I1 is then opened and oil from the reservoir I3 is forced into the cylinder by air pres' sure. It will be seen that'the flow of the oil past the valve i1 is thus extremely rapid in both di- 'rections so that the friction encountered is suf- 10 flciently great to raise the oil temperature to such a point that in some installations the packing has been burned from the piston 8, and other damage has been done. To overcome this condition it has been the practice to limit the length 15 of stroke of a press operating at a given speed, and similarly to restrict the number of strokes per minute of a press having a given length of stroke. It will be appreciated that the velocity of the oil through the passage l5 depends on these factors, and hence the temperature rise of the oil is similarly dependent.

In order to increase the working capacity of the press, and permit an increase in operating speed of stroke, the 35 of a press having a given length present invention provides means, to control the working temperature of the oil used in the hydraulic cushion. This means preferably includes metallic coils 25 disposed-in the bottom .of the reservoir l3 and constantly immersed in the liq- 30 uid. The coils may be made of any suitable material and may be of any desired thickness, depending on the co-efflcient of heat conductivity of the material used. The coils are preferably helical in form so as to-expose the maximum sur- 35 face in a'minimum lateral area. At each end the coil is brought out through the wall of the reservoir to connect with a suitable union- 2'! fixed to the reservoir.

As shown in Fig. 4, the cooling medium for the coils 25 is taken from a suitable supply main 3| through an intake pipe 33 having a valve 1 35 disposed therein. The pipe 33 isconnected to each of the coils through branches 3! and 39,

terminating in respective unions 21 and ,each

controlled by a suitable valve 40. At the opposite end the coils are connected to discharge pipes 42 and 44 which join in a main discharge pipe 46 connected to a sewer or other outlet. It will thus be seen medium circulated through the coils may be regulated to control the working temperature of the liquid used in the hydraulic cushion. If it is desired to lower the temperature slightly, the

valve 35 may be opened to permit a slow circula- 66 that the quantity of cooling 50 having an uninterrupted 2 tion of the cooling medium, while it it is desired to lower the temperature of the cushioning liquid to a greater extent, the valve 3'5 may be opened to permit a greater circulation of the cooling medium.

While the invention has been described in connection with a particular type of hydraulic cushion, it should be expressly understood that it is capable of use with any other known type of cushioning means which employs a liquidhaving a tendency to become hot in use. Obviously, numerous changes in the form and disposition of the coils may be made without departing from the invention as defined in .the appended claims.

What I claim is: a

1. In a press of the character described having a, cushion pad and a piston carried by said pad, a cylinder formed to receive said piston and transverse passage at its lower end, a fluid containing receiver associated with the cylinder and having communication with the latter through said transverse passage, means for forcing fluid from the receiver into the cylinder to actuate the piston, a pair of spaced interconnected cooling means in the receiver in the path of fluid forced through the transverse passage, each of said interconnected cooling means having a portion thereof in alinement with the uninterrupted passage, and means connected to the cooling means for controlling the latter.

2. In a press of the character described having a cushion pad and a piston carried by said pad, 9. cylinder formed to receive said piston and having an uninterrupted transverse passage at its lower end, a fluid containing receiver associated with the cylinder and having communication -with the latter through said transverse passage,

means for forcing fluid from the receiver into the cylinder to actuate the piston, a pair of spaced longitudinally extending interconnected coolin coils in' the receiver in the path of fluid forced through the transverse passage, each of said interconnected cooling coils having a portion there.

of in alinement with the uninterrupted passage, and means connected to the cooling coils for controlling the latter.

, FREDRICH J. RODE. 

